Alarm for detection of pressure surges in a borehole



March 14, 1961 J. A. RICKARD 2,974,629

ALARM FOR DETECTION OF PRESSURE SURGES IN A BOREHOLE Filed Dec. 10, 1958 2 Sheets-Sheet 1 FIG. I.

FIG. 2.

INVENTOR.

JAMES A. RICKARD,

\ BY ,KJAM/ ATTORNEY.

March 14, 1961 J. A. RICKARD 2,974,629

ALARM FOR DETECTION OF PRESSURE SURGES IN A BOREHOLE Filed Dec. 10. 1958 2 Sheets-Sheet 2 FIG. 4

FIG. 5.

INVENTOR.

ATTORNEY.

tices, 1954, Paper 901-30-H. Until ALARM FOR'DETECTION OF PRESSURE SURGES IN A BOREHOLE James A. Rickard, Houston, Tex., assignor, by mesne assignments, to Jersey Production Research Company, Tulsa, Okla., a corporation of Delaware Filed Dec. 10, 1958, Ser. No. 779,337

4 Claims. 01. 116-74) This invention relates to the drilling of boreholes in the earth and more particularly to the prevention of pres sure surges produced during manipulations of well pipe in a borehole.

A very important problem encountered during drilling of boreholes in the earth for the production of hydrocarbons is that of lost returns in rotary drilling of wells. When mud returns to the earths surface are lost, normal drilling must cease. The damaged area must be treated and the lost mud replaced.

'Many cases of lost returns are due to cavernous formations and other factors essentially beyond the drillers control. In some areas, however, the evidence is clear that lost returns are cansed'by pressure surges produced by pipe handling operations at the surface.

lPressure surges can produce a number of undesirable effects, all of which are not as obvious as lost returns. In some cases, alternate positive and negative surges can partially remove the mud cake and allow mud filtrate to invade the formation. This may either damage the rocks directly or efiectively flush out gas or oil. In either case, possible producing formations may be overlooked.

In other cases the physical shock of pressure surges may deform or fracture .the walls of the hole. This can produce stuck drill pipe or difiicult drilling conditions and maybe a major factor in increasing drilling costs. In extreme cases the formation may be damaged so badly that it breaks down andallows mud to enter in large quantities.

Various American Petroleum Institute publications have discussed the efiects of positive pressure surges produced by running pipe into boreholes and the theoretical results for such positive surges.

See, for example, American Petroleum Institute Drilling and Production Pracrecently, however, therehas been a definite lack of knowledge of the details of pressure surges produced in running and pulling pipes. In the past it has been tacitly assumed that the positive pressure component was the only surge produced in running pipe into a borehole, and that pressure surges were due solely to the velocity of the pipe running in, thus producing frictional drag. This is an over-simplified view of a rather complex problem. There are actually at least five separate and independent surge components produced as pipe is started from rest, allowed to move into a hole, and then stopped. These componentsare:

(l) A positive surge component produced by breaking the gel of the mud; v

=(2) A positive surge component produced by accelerating the standing mud column; (3) A positive surge component produced by accelcrating the mud immediately below the drill pipe;

(4) A positive surge component produced by frictional drag of the mud on both the pipe and the walls of the hole; and

(5') A negative surge'component produced bydecelof apparatus including a travelling block 5, a

. 2 crating the moving mud column as the pipe comes to a stop.

The ordinary sequence of drilling operations includes both lowering of the pipe as described above and also lifting of the pipes out of the slips prior to the lowering operation. It may thus be seen that in ordinary field manipulations, as many as ten individual components (some of which may be negligible) may be effective in producing a single pressure surge.

It is anticipated that these components may not necessarily be additive, for many of them may occur at different-times. The acceleration surge, for example, is usu ally highest when the velocity is very low. The frictional drag surge which accompanies maximum pipe velocity occurs when the acceleration component is zero. To determine if the causes and sequence of pressure surge components postulated above were correct and to determine the relative magnitude and importances of various surge components, experimental determinations of pressure surges in the field have been made. The results of these experimental determinations indicate that there are three predominant pressure surges; namely (1) a negative surge occurring as the pipe is picked up from the slips, (2) a positive surge occurring when pipe velocity is maximum, (3) one or more negative surges occurring as the drilling pipe is decelerated by applying the brakes on the drawworks.

It may be thought that an ideal way to control pressure surges would be to have the surge components monitored at all times and to have the actual pipe running operations under automatic control from the measured pressure surges. This is not feasible at the present time with existing equipment. Field drilling in some respects is more an art than a science, and extensive field experience has'indicated that manual control of the pipe handling operations is advisable. Since the driller himself controls the pipe handling apparatus, it is apparent that in order to reduce or prevent pressure surges it is necessary to indicate to the driller when the prmsure surges become large enough to be dangerous. It is obvious from the above discussion that this is tantamount to indicating to the driller when the pipe velocity and acceleration exceed critical values. In order for a warning device to be used at all on a drilling rig, it must be completely simple. Past experience has proven that the usefulness of a device used on a rig is inversely proportional to its, complexity and sophistication.

Any device used to indicate the velocity and accel: eration of a .movingpipe on'a drilling rig therefore should be (1) free from maintenance, (2) simple to construct, (3) easy to install and replace, (4) rugged, (5) failureproof, and (6) reasonably accurate.

The invention will be described with reference to the accompanying drawing, wherein:

Fig. 1 is an illustration of the invention'in combination with pipe manipulating apparatus such as is used with a drilling rig, and

Figs. 2 and 3 are illustrations of warning apparatus respectively warning of excessive pipe velocity and excessive pipe acceleration.

Fig. 4 is an enlarged view of the apparatus of Figs. 2 and 3, more perspicuously illustrating the details of construction thereof.

Fig. 5 is a fragmentary, sectional view of the wheel and axle shown in Fig; 4 taken along section 5-5, more perspicuously showing the position of the slot 27 in the axle.

Fig.6 is a fragmentary, elevational view paratus of Fig. 4 taken along line 66.

In Fig. 1 there is shown a well pipe 6 being lowered into the earth through a rotary drilling table 4 by means hook 10,

of the apand elevator bales 12 connected to an elevator 8. A sheave assembly 9 is provided at the top of the drilling rig (not shown). The sheave assembly 9 may include the usual crown block 14, through which is run a rope 7 that extends from drawworks 3 through the crown block 14 and the travelling block 5 in the usual manner. The drawworks 3 may be driven by a prime mover such as an internal combustion engine 1. In addition to the rope 7 and crown block 14, the sheave assembly 9 includes a rope 16 and a pair of pulleys 17. One end of the rope 16 is affixed to the travelling block 5 and the other end is afiixed to a Weight 18. Rope 16 passes over the pulleys 17 to drive pulley Wheel 13 connected to a housing 11. The housing 11 may be located on the drilling floor. The angular velocity of pulley wheel 13 is a direct function of the linear velocity of the travelling block 5 and the well pipe 6.

In Figs 2, 3, 4, and 6 there is shown a small, fairly heavy mass 21 connected to the wheel 13 so as to rotate with the wheel 13. Wheel 13 is connected to its axle 23 so that both rotate together. The mass 21 may be connected to axle 23 by means of a flexible connectingv means 25, Which may be a flexible steel rod or a rod of rubber or rubber-like material. The rod 25 extends through a slot 27 in axle 23 (illustrated more perspicuously in Fig. 5) so as to pass through the axis of rotation of wheel 13 and to move in reciprocation in the slot 27. A spring 28 is connected between the axle 23 and the mass 21 so as to hold the mass 21 at a predetermined distance from the axis of rotation of Wheel 13 when the wheel 13 is not moving. The ends of spring 28 are inserted in small holes in the mass 21 and axle 23, and the ends of the spring 28 are welded to mass 21 and axle 23 as indicated by welds 21A and 23A. The spring 28 spirals around rod 25. For the purpose of initiating an aural signal when the angular velocity of wheel 13 exceeds a predetermined velocity, a warning indicating device 15 is affixed to housing 11 at a predetermined distance from the axis of rotation of wheel 13. This is best illustrated in Figs. 4 and 6. For the purpose of initiating an aural signal when the acceleration or deceleration of the wheel is greater than predetermined values, warning initiating devices, here shown as gongs 19 and 20, are affixed to the wheel on each side of weight 21, as can be most clearly seen in Fig. 6. The distance of gongs 19 and 20 from the quiescent position of mass 21 is determined by the acceleration and deceleration of pipe 6 at which a warning is desired. As the weights are moved away from the quiescent position of mass 21, the acceleration or deceleration required for the mass to strike the gongs 19, 20 will increase correspondingly.

As the linear velocity of travelling block 5 and the angular velocity of wheel 13 increases, mass 21 will move outwardly from the axis of rotation of wheel 13 as a function of the angular velocity of Wheel 13, and thus as a function of the linear velocity of travelling block 5 (see Fig. 2). If the velocities are sufliciently large, mass 21 will strike gong 15 to indicate to the drilling rig operator that the pipe 6 is being lowered at an excessively high velocity. Furthermore, if the pipe 6 is accelerated too rapidly, mass 21 will move in a circumferential direction to the left to strike gong '19; if the travelling block 5 is decelerated too rapidly, the mass 21 will move in a circumferential direction to the right and will strike gong 20. Thus, the drilling rig operator is warned that the limits that have been set for pipe velocity and for accelerating and decelerating the pipe 6 are being exceeded.

Manifestly, various modifications may be made to the invention without departing from the spirit and scope of the invention, and it is desired that the above description be taken as illustrative and not in a limiting sense. a

What is claimed is:

1. Apparatus for sounding a warning when either the velocity, acceleration, or deceleration of a well pipe lowered through a borehole exceeds predetermined limits; comprising: means for vertically manipulating the well pipe including a travelling block adapted to be connected to the well pipe and a rope and pulley system connected to said travelling block; awheel and an axle therefor connected to the rope and pulley system so that the velocity of rotation of said wheel and axle is a direct function of the linear velocity of said travelling block; a small, heavy mass; flexible connecting means connecting said mass to said wheel for rotation therewith, including a flexible rod connected to said mass, slidably extending through said axle of said wheel, and spring means connecting said mass to said wheel to hold said mass at a given distance from said axle when said wheel is at rest and to position said mass at radial distances from the axis of rotation of said wheel varying with the angular velocity of said wheel; said flexible connecting means being further adapted to move said mass circumferentially on said wheel in accordance with the acceleration and deceleration of said wheel; first and second means positioned on each side of the reference position of the mass in the plane of rotation thereof adapted to initiate an aural signal responsive to movement of said mass through given distances in either direction from the normal position thereof; and third means positioned a given distance from said axle of said wheel adapted to initiate an aural signal when striken by said mass upon radial movement of said mass to said given distance from said axle upon increase in the angular velocity of said wheel to a given angular velocity.

2. Apparatus for sounding a warning when either the velocity, acceleration, or deceleration of a well pipe lowered through a borehole exceeds predetermined limits, comprising: means for vertically manipulating the well pipe including a travelling block adapted to be connected to the well pipe and a rope and pulley system connected to said travelling block; a wheel and an axle therefor connected to the rope and pulley system so that the velocity of rotation of said wheel and axle is a direct function of the linear velocity of said travelling block; a small, heavy mass; flexible connecting means connecting said mass to said wheel for rotation therewith, including a flexible rod connected to said mass and slidably extending through said axle, and a coil spring connected to said mass and to said axle to hold said mass at a given distance from said axle when said wheel is not rotating and further to position said mass at radial distances from the axis of rotation of said wheel varying with the angular velocity of said wheel, said connecting means being further adapted to move said mass circumferentially on said wheel in accordance with the acceleration and deceleration of said wheel; means positioned on said wheel in the plane of rotation of said mass adapted to initiate an aural signal responsive to movement of said mass through a given distance from the normal position thereof on said wheel as the result of acceleration or deceleration of angular movement of said wheel; and means positioned a given distance from said axle of said wheel adapted to initiate an aural signal when stricken by said mass upon movement of said mass to said given distance from said axle upon increase in the angular velocity of said wheel to a given angular velocity.

3. Apparatus as defined in claim 1 wherein said first, second, and third means are gongs.

4. Apparatus for sounding a warning when either the velocity, acceleration, or deceleration of a well pipe lowered through a borehole exceeds predetermined limits, comprising: a travelling block adapted to be connected to the well pipe; a rope and pulley system connected to said travelling block for vertical manipulation of said travelling block; a wheel and axle therefor in said rope and pulley system, angularly driven by vertical movement of said travelling block so that the angular velocity of said wheel and axle is proportional to the linear velocity of the travelling block; a flexible plunger slidably passing through the axle of said wheel and extending radially from said axle; a coil spring afiixed at'opposite ends to said plunger and to said axle adapted to hold said plunger at a given position when said wheel is at rest, and to permit radial movement of said plunger when said wheel rotates, said plunger being connected to said wheel to rotate therewith; said plunger being adapted to flex circumferentially in one direction or the other from a normal position thereof in accordance with the acceleration or deceleration of said wheel and to move radially from said axle in accordance with the angular velocity of the wheel; first gong means aflixed to said wheel at a position whereat it will be stricken by said plunger when the angular acceleration of said wheel reaches a predetermined value; second gong means aflixed to said wheel at a position whereat it will be stricken by said plunger when the angular deceleration of said wheel reaches a predetermined value; and a third gong means positioned a distance from the edge of said wheel whereat it will be stricken by said plunger upon radial movement of said plunger caused by increase in the angular velocity of said wheel to a given angular velocity.

References Cited in the file of this patent UNITED STATES PATENTS 

